PEALD (Plasma-Enhanced Atomic Layer Deposition) causes a precursor to adsorb to a substrate, for example, and subsequently generates oxygen plasma, thereby forming an oxide film on the substrate. For example, the substrate includes a certain thin film or a pattern as a covered object on a surface, and an oxide film can be formed on the covered object through PEALD. The covered object is called an underlying film because this film serves as an underlayer for the oxide film. The oxygen plasma can be generated by providing oxygen gas for a reaction space including an RF plate and by applying a high-frequency power to the RF plate.
Depending on a type of the underlying film or an oxidation source, the underlying film may be damaged as the oxide film is formed through PEALD. Such damage may sometimes thin the underlying film.